Chip Collier a0972c2b1b Add some more helpful errors to BevyManifest when it doesn't find Cargo.toml (#9207) ... When building Bevy using Bazel, you don't need a 'Cargo.toml'... except Bevy requires it currently. Hopefully this can help illuminate the requirement. # Objective I recently started exploring Bazel and Buck2. Currently Bazel has some great advantages over Cargo for me and I was pretty happy to find that things generally work quite well! Once I added a target to my test project that depended on bevy but didn't use Cargo, I didn't create a Cargo.toml file for it and things appeared to work, but as soon as I went to derive from Component the build failed with the cryptic error: ``` ERROR: /Users/photex/workspaces/personal/mb-rogue/scratch/BUILD:24:12: Compiling Rust bin hello_bevy (0 files) failed: (Exit 1): process_wrapper failed: error executing command (from target //scratch:hello_bevy) bazel-out/darwin_arm64-opt-exec-2B5CBBC6/bin/external/rules_rust/util/process_wrapper/process_wrapper --arg-file ... (remaining 312 arguments skipped) error: proc-macro derive panicked --> scratch/hello_bevy.rs:5:10 | 5 | #[derive(Component)] | ^^^^^^^^^ | = help: message: called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" } error: proc-macro derive panicked --> scratch/hello_bevy.rs:8:10 | 8 | #[derive(Component)] | ^^^^^^^^^ | = help: message: called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" } ``` ## Solution After poking around I realized that the proc macros in Bevy all use bevy_macro_utils::BevyManifest, which was attempting to load a Cargo manifest that doesn't exist. This PR doesn't address the Cargo requirement (I'd love to see if there was a way to support more than Cargo transparently), but it *does* replace some calls to unwrap with expect and hopefully the error messages will be more helpful for other folks like me hoping to pat down a new trail: ``` ERROR: /Users/photex/workspaces/personal/mb-rogue/scratch/BUILD:23:12: Compiling Rust bin hello_bevy (0 files) failed: (Exit 1): process_wrapper failed: error executing command (from target //scratch:hello_bevy) bazel-out/darwin_arm64-opt-exec-2B5CBBC6/bin/external/rules_rust/util/process_wrapper/process_wrapper --arg-file ... (remaining 312 arguments skipped) error: proc-macro derive panicked --> scratch/hello_bevy.rs:5:10 | 5 | #[derive(Component)] | ^^^^^^^^^ | = help: message: Unable to read cargo manifest: /private/var/tmp/_bazel_photex/135f23dc56826c24d6c3c9f6b688b2fe/execroot/__main__/scratch/Cargo.toml: Os { code: 2, kind: NotFound, message: "No such file or directory" } error: proc-macro derive panicked --> scratch/hello_bevy.rs:8:10 | 8 | #[derive(Component)] | ^^^^^^^^^ | = help: message: Unable to read cargo manifest: /private/var/tmp/_bazel_photex/135f23dc56826c24d6c3c9f6b688b2fe/execroot/__main__/scratch/Cargo.toml: Os { code: 2, kind: NotFound, message: "No such file or directory" } ``` Co-authored-by: Chip Collier <chip.collier@avid.com>		2023-07-19 12:05:04 +00:00
..
attrs.rs	update syn, encase, glam and hexasphere (#8573)	2023-05-16 01:24:17 +00:00
lib.rs	Add some more helpful errors to BevyManifest when it doesn't find Cargo.toml (#9207)	2023-07-19 12:05:04 +00:00
shape.rs	Don't panic in macro shape validation (#3647)	2022-01-15 22:14:43 +00:00
symbol.rs	Implement and require #[derive(Component)] on all component structs (#2254)	2021-10-03 19:23:44 +00:00